Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED RESULTS
Revenues	$ 440,135	$ 358,693	$ 293,769	$ 215,869	$ 261,445	$ 248,566	$ 211,848	$ 167,672	$ 1,308,466	$ 889,531	$ 1,000,825
Income (loss) income from continuing operations before taxes	30,319	10,430	6,239	(3,021)	814	(3,908)	(9,801)	(19,837)	43,967	(32,732)	(80,497)
Tax expense (benefit)	1,372	23	190	0	(449)	(18)	0	(2,398)	1,585	(2,865)	195
Net income (loss) from continuing operations	28,947	10,407	6,049	(3,021)	1,263	(3,890)	(9,801)	(17,439)	42,382	(29,867)	(80,692)
Loss from discontinued operations, net of taxes	(374)	238	223	(2,087)	(451)	(17,423)	(912)	(2,097)	(2,000)	(20,883)	(4,447)
Net income (loss)	$ 28,573	$ 10,645	$ 6,272	$ (5,108)	$ 812	$ (21,313)	$ (10,713)	$ (19,536)	$ 40,382	$ (50,750)	$ (85,139)
Basic
Continuing operations (in dollars per share)	$ 0.64	$ 0.23	$ 0.14	$ (0.07)	$ 0.03	$ (0.09)	$ (0.22)	$ (0.39)	$ 0.93	$ (0.67)	$ (1.83)
Discontinued operations (in dollars per share)	$ (0.01)	$ 0.01	$ 0.00	$ (0.04)	$ (0.01)	$ (0.39)	$ (0.02)	$ (0.05)	$ (0.04)	$ (0.47)	$ (0.10)
Total (in dollars per share)	$ 0.63	$ 0.24	$ 0.14	$ (0.11)	$ 0.02	$ (0.48)	$ (0.24)	$ (0.44)	$ 0.89	$ (1.14)	$ (1.93)
Diluted
Continuing operations (in dollars per share)	$ 0.56	$ 0.21	$ 0.14	$ (0.07)	$ 0.03	$ (0.09)	$ (0.22)	$ (0.39)	$ 0.88	$ (0.67)	$ (1.83)
Discontinued operations (in dollars per share)	$ (0.01)	$ 0.01	$ 0.00	$ (0.04)	$ (0.01)	$ (0.39)	$ (0.02)	$ (0.05)	$ (0.04)	$ (0.47)	$ (0.10)
Total (in dollars per share)	$ 0.55	$ 0.22	$ 0.14	$ (0.11)	$ 0.02	$ (0.48)	$ (0.24)	$ (0.44)	$ 0.84	$ (1.14)	$ (1.93)
Weighted-average common shares outstanding:
Basic (in shares)	45,115,000	44,826,000	44,628,000	44,474,000	44,410,000	44,409,000	44,369,000	44,239,000	44,761,178	44,357,470	44,050,013
Diluted (in shares)	53,053,000	52,654,000	48,571,000	44,474,000	45,075,000	44,409,000	44,369,000	44,239,000	49,655,321	44,357,470	44,050,013